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b=Vhuqq3dhS0xj/pd9jp9IoVKDsg24dq5X2+kEEIBjB+a3vki3RCwS4uXdfJC4jqTXJ thxERrpgvXlbZtgTioLwixWVxFgiZUzOmhCn0EbPB0XODc4QSl1IVOk2OzQ56ZULUD D/eOxK4ZSBkWfhM21240hACSxmQV00dGRsxfsSsg= Date: Mon, 31 Aug 2026 16:45:31 -0700 From: Andrew Morton To: "Li Zhe" Cc: , , , , , , , , , , , , , , , Subject: Re: [PATCH v11 0/7] mm: optimize zone-device memmap initialization Message-Id: <20260831164531.be5a8fa210401830e85eb974@linux-foundation.org> In-Reply-To: <20260831111638.76012-1-lizhe.67@bytedance.com> References: <20260831111638.76012-1-lizhe.67@bytedance.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: 61wmbj3zd4jqwfts3whnya48cjtewpp5 X-Rspamd-Queue-Id: 672A4100007 X-HE-Tag: 1788219934-207424 X-HE-Meta: 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 m/zozD/E 6kuKL7ciDflJlR4o7gJe2PLbZI+aZHbs6LRv0EcwyOaKUK9Tz6lKvTlVvI5tk03/2CnbbCJWRweTx5RrworxLAQWW9ACWwlJIVIafqs/xB6sJF/8gOZxF0uVh71U0ADJBFOZd45TQUx5ScI5lTuz4j10NuGPwr+V8X+Wd76EYbLmD0iETJl5KOsy8vPKkv02WtSv/KviH+Z4AAGXfM71HDyPh59DZt5fQ0kGQY23eVEl616DbwHpPaguNg0Gd0BsICBTDSSh55b8fvgrSB3di78TbQtte2VReknFnAK/rqK7GohWEyDs6u8wEL10S8Zz5my7ijOmK/x6hiJQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 31 Aug 2026 19:16:31 +0800 "Li Zhe" wrote: > memmap_init_zone_device() can take a noticeable amount of time when large > pmem namespaces are bound or rebound, because it initializes nearly > identical struct page descriptors one PFN at a time. This series reduces > that ZONE_DEVICE memmap initialization overhead by reusing prepared > struct page templates and, on x86, using memcpy_nontemporal() for the > template copy path. > > ... > > This reduces the average memmap initialization time measured during > rebind by about 48.0% for nd_pmem and 41.6% for dax_pmem on that arm64 > VM setup. Since this arm64 setup does not use the x86 MOVNTI fast paths, > the result also suggests that the generic template-copy optimization can > benefit architectures without an architecture-specific > memcpy_nontemporal() backend. Well that's nice. Sashiko seems to have found some new things to complain about: https://sashiko.dev/#/patchset/20260831111638.76012-1-lizhe.67@bytedance.com